Jamieson, Fausset & Brown

sometime--"once." walked . . . when ye lived in them--These sins were the very element in which ye "lived" (before ye became once for all dead with Christ to them); no wonder, then, that ye "walked" in them. Compare on the opposite side, "living in the Spirit," having as its legitimate consequence, "walking in the Spirit" (Gal 5:25). The "living" comes first in both cases, the walking follows.